## Eduardo D. Sontag

Eduardo D. Sontag received his Licenciado in Mathematics at the University of Buenos Aires (1972) and a Ph.D. in Mathematics (1977) under Rudolf E. Kalman at the University of Florida. From 1977 to 2017, he was at Rutgers University, where he was a Distinguished Professor of Mathematics and a Member of the Graduate Faculty of the Departments of Computer Science of Electrical and Computer Engineering and the Cancer Institute of NJ.

Richard Bellman was a paragon of deep foundational thinking and interdisciplinary work, so I am deeply grateful to receive an award that honors him. It is especially meaningful that the prize is awarded by the Automatic Control Council, which brings together such disparate areas of applications in engineering, mathematics, and the sciences.

Exactly 50 years ago, as an undergraduate in Buenos Aires looking for a senior project, I discovered the work of Rudolf Kalman, which sparked a stable and robust attraction to control theory that continues to this day. One of my professors met Kalman at a conference, which led to Kalman inviting me to be his student. Kalman’s rigorous mathematical approach inspired research excellence, deep thinking, and clear exposition. The 1970s witnessed an explosion of new and exciting ideas in systems theory, and many of the leaders in the field visited Kalman's Center. I was extremely lucky to have the opportunity to learn from all of them.

After my PhD, I went to Rutgers, where I was fortunate to collaborate with Hector Sussmann, and to learn so much from him.

Five years ago, I was recruited by Northeastern University, where I have fantastic colleagues, especially Mario Sznaier and Bahram Shafai.

Of course, I am grateful to all who influenced my work, too many to credit here, and to those who applied, enriched, and extended my initial ideas. At the risk of sounding presumptuous, let me share some thoughts about research in systems and control theory. First, it is important to formulate questions that are mathematically elegant and general. Paradoxically, general facts are often easier to prove than special ones, because they are stripped of irrelevant details. Second, we should strive to simplify arguments to their most elementary form. It is the simplest ideas, those that look obvious in retrospect, that are the most influential, as Bellman’s dynamic programming so beautifully illustrates. Third, we should be aware of the essential connection between theory and applications. Applications provide the inspiration for an eventual conceptual synthesis. Conversely, theory is strengthened and refined by working out particular cases and applications. Fourth, one should be cautiously open to new ideas, even those orthogonal to current fashion. But not all new ideas are good: novelty by itself is not enough. Finally, we should not lose sight of the fact that, while fun and intellectually challenging, our ultimate objective is to improve the world through scientific and engineering advances.

Which brings me back to Richard Bellman’s heritage, which we honor today. Years after his foundational work on optimality, Bellman turned to biology and medicine, even starting a mathematical biology journal. I am sure that the mechanistic understanding of behavior at all scales, from cells to organisms will lead to control and elimination of disease and the extension of healthy lifespans. I find immunology and its connections to infectious diseases and cancer to be a fascinating field for systems thinking. In addition, the associated engineering field of synthetic biology will lead to new therapeutic approaches as well as scientific understanding, and new mathematics and control problems suggest themselves all the time. In my view, the main value of systems and control to molecular biology will not be in applying deep theoretical results. Instead, conceptual ideas like controls, measurements, robustness, optimization, and estimation are where the main impact of our field will be felt.

Thank you so much.

June 9, 2022

Atlanta, GA USA

ACC 2022